There is no advantage to logging out and logging back in to Pokémon Go. As a result, you will not be marked as a cheater. The "bouncing around" can happen regardless of how recently you logged in, and would be interpreted as a "hardware fault", so to speak. Not an exploit.
I have previously had a lot of issues with GPS in the game, and found a fix that involved having to completely shut down the game. I do this quite a lot, and do not notice any sudden appearance of Pokémon, when I get back into the game. At the very least, the action of logging in is not spawning more Pokémon.
If this was actually a bug that caused more Pokémon to spawn, you would consider it an "exploit". For further confidence, rest assured that "exploiting an exploit" requires deliberation and intentional understanding. The simple fact that you are closing the application to fix an apparent lock-up is enough to determine that even if this was giving you an advantage, you would not typically be defined as cheating.