I had something similar to this a few months ago, but it wasn’t after PE it was after sex. It was really strange because PE conditioned my unit pretty good. I have never had any fears of breaking my dick when trying new techniques etc.
It was like the bump you talked about, mine was a bit bigger though (nearly an inch) but also a general swelling around the bump. No pain. Girth is normally 5.8 or 5.9 but it must have been 6.2 or so at that time. Pretty scary. Luckily the next day it was gone and I haven’t had a problem since. Really hard to explain could have caused it.
For your case, I would be worried if it keeps coming back when you jelq or pump. As long as it doesn’t affect your unit in terms of performance and no pain, it doesn’t seem like much to worry about, but still never a good sign.