I'm sure it's very related to your new substrate depth. I remember adding a couple more inches of substrate in my last cleaning and my frogs would burrow for 2-3 days which kinda annoyed me because I couldn't find them and I did not want the extra substrate to encourage aestivation. I know they would stay in there longer if I didn't get them out so I followed Grif's advise to only provide enough substrate for the frog to cover itself without going 2-3 inches under the surface.