A bug without context is not a bug, it's a fluke. The problem could be your code, it could be a third party library, it could be the hardware, or it could be solar radiation causing a single bit to flip on it's own. If you can't reproduce it with at least some regularity (even if only "it happens once every 10 or 20 times I do X"), it's not much better than your tester telling you "Something somewhere went wrong somehow - fix it".