The elastomer roofs will expand as the temps warm up. Perhaps this was the first time you checked it in warm weather?
Having said that, I have noticed only a small of expansion on our roof in warm weather.
Hard to tell how much expansion you have fom the pics.
Keep in mind TPO is different from "rubber" roof.
EC have 3 yr structural warranty and IIRC 12 years on roof. Sure won't hurt to bring it by BP's place next time your up there so he can look at it...
Edit; on second look at your pics...I don't see anything unusual for a TPO roof.