Water pressure spikes?

Hi,
I installed a PRV and Expansion tank about 6 months ago and I have the pressure set in my home for 65 psi. I accidently left the pressure gauge connected to my water heater drain spigot (lowest point in house) after I did the job. I noticed that the nominal pressure is at the 65psi however I must be getting spikes up to 95 psi since the needle that tracks maximum was at that level. I reset it and rechecked a few weeks later and I got the same reading of about 95psi.
Is this normal?
I used a 2.5 gal expansion tank with a 50 gal heater, is this too small?
I would appreciate any comments. I want to make sure I won't have any problems.
Thanks,
Gary

I would check the pressure of the expansion tank with the water drained down.
If the air escapes from the rubber bladder, then it's not doing it's job.
It may be time for a tire pump and air gauge.