Who knows what the reason was for the increase then the decrease in share price. Many local banks increased on 9/16 but PFS may have been more heavily shorted so it went up more. I don't think that traders look at fundamentals only momentum.
Options expired on Friday but it doesn't trade all that many options.
The other week ISBC increased for no apparent reason.

There have many mergers recently but not of local small banks. It would be a pleasant surprise if PFS was acquired for a premium.
There are not many fully converted small banks with as many branches and assets as PFS has being valued at only 0.79 of book value.