Will I have immigration issues re-entering Thailand after a short visa exemption?

with the entry history you outline you run a slim to none chance of being questioned on entry. I personally wouldn't worry about it at all.

If you have a long history of doing this there might be a problem. The thing is we are not immigration officers, its up to the officer who is stamping you in at the time.

If you want to come in visa exempt which gives you 30 days plus another 30 days by going to the local immigration office. I would suggest bringing the 3 proofs.

20k baht or equivelant currency in cash, hotel booking confirmation and fligt ticket out of thailand within the 60days.

Is that your only previous visit to Thailand? You've never been prior to that? What is your nationality?

Maybe. It all depends on if the immigration officer thinks you’re taking advantage of the system.