Told in early May that I am June 1 layoff. Company refusing to pay PTO for May

I was told in early May that I would be laid off effective June 1st. In fact, I was told that I "would have been" laid off in March if I wasn't on FMLA leave at the time (newborn baby). In May, on being given notice of my layoff, I asked to use PTO to supplement my Family Leave pay for the remainder of my time at the Company. The employer did supplement pay in my final paycheck, but did not do so for pay in the first half of May, and is unresponsive to multiple emails and phone calls asking why this was the case and/or asking when this would be paid. There is "only" about $1000 at stake here. The severance agreement (1 week of pay per year of service) is due to be signed in about two weeks, and I fear that the company is stonewalling me until that date to avoid paying the PTO.

I also believe the severance agreement, as far as I can see illegally, waives my claim to a year-end safe harbor 401k match (from 401k SPD, you do not need to be employed to receive the year-end match). I have asked to add an addendum to address the language in the severance agreement but the company has not responded to these communications either.

Are either of these actions normal - what can I do - should I retain a lawyer?