Night Vision Pulsar Thermion 2 XG50 losing zero

[bd05320]

Has anybody had any trouble with this scope losing zero when exposed to single digit temps? I have had this happen twice now over the last month. The first time it happened i checked and retightened all the screws from the bases all the way to the ring caps. After doing this i tested in 20 degree temps with no issues. Last night however it got back down in the single digits and after hunting i found that the impact had shifted 8 inches lower and 4 inches to the right at 200yds. I checked the zero before going out that night and everything was fine. Upon finding out the poi had moved i shot the rifle both warm/cold and the poi remained the same. I then checked that all the mounting hardware was tight and found nothing out of the ordinary. Called Pulsar this morning and they recommended trying reverting everything back factory default settings and rezeroing before i resort to sending it in. Upon doing that and rezeroing, the poi has not shifted when i cycled the gun from cold to warm multiple times this morning. Im hoping this solved the problem somehow. Just looking for some opinions before i end up having to send the scope back in to Pulsar as its been hard to trust the scope for accuracy as of late when it gets cold.