Agree with Jason. Check your humidity, especially since I see you are from Calgary

it can be nothing, just seasonal, but to be sure if you need to adjust anything - please answer to the questions below, and if all is good, no need to worry
“Trouble in the Frog Enclosure” The following information will be very helpful if provided when requesting assistance with either your frog or enclosure. To help with your questions, please utilize the below list and post the information in the proper forum area to get advice from FF members that keep the same frog. This will allow for little confusion and a faster more informed response.
1. Size of enclosure?
It's a 1ft x 3ft roughly and 1 ft tall
2. # of inhabitants - specifically other frogs and size differences?
One female bullfrog
3. Humidity?
The coco husk gets soaked so it's very moist, and i mist a few times a day to keep the surface fairly dark
4. Temperature?
I just ordered a new thermometer, digital probe, but have two -100 heat lams, usually one going at a time, regular and one red night time
5. Water - type - for both misting and soaking dish?
De-chlorinated water, I have a water dish that i place the frog in during/after eating, but she jumps out after she's done going to the bathroom
6. Materials used for substrate?
Coco husk, the other half is sand with moss (changing this side to a huge swimming area)
7. Enclosure set up i.e. plants (live or artificial), wood, bark and other materials. - How were things prepared prior to being put into the viv?
Had one plant (made sure it was frog safe but just removed today) one tree bark hiding hut
8. Main food source?
Ate her first mouse today, been doing super worms for the past year
9. Vitamins and calcium? (how often?)
I would sprinkle cricket duster on the super worms so they could eat it
10. Lighting?
2-100watt bulbs, one running at a time. regular and red night time. Just ordered a black night lamp and a blue incandescent
11. What is being used to maintain the temperature of the enclosure?
Thermometer that didn't seem to be working, ordered a new digital probe
12. When is the last time he/she ate?
5 minutes ago, eats regularly about one/twice a week
13. Have you found poop lately?
Saw her taking one just after eating the mouse
14. A pic would be helpful including frog and enclosure (any including cell phone pic is fine)
Will take one and post a new thread to get opinions on enclosure when I change the water area this weekend
15. Describe frog's symptoms and/or recent physical changes; to include it's ventral/belly area.
None
16. How old is the frog?
About 2 and a half years
17. How long have you owned him/her?
About 2 and a half years
18. Is the frog wild caught or captive bred?
Bought from a pet store when it was a baby
19. Frog food- how often and if it is diverse, what other feeders are used as treats?
Superworms, a few horned worms, first mouse today =]
20. How often the frog is handled?
Only when it is time to feed...1/2 times a week
21. Is the enclosure kept in a high or low traffic area?
Low traffic, my bedroom
22. Describe enclosure maintenance (water changes, cleaning, etc)