Forest Green question...

[BruPri]

Hello, I recently purchased a Forest Green and want to know if what I'm hearing is normal.
I have a MIM Telecaster/VoxAC4TV and Marshall Class5, I'm hearing the same thing on either amp.
When the compressor is switched to Compressor and engaged, when I play my open E and A strings together, I get a very pronounced warbling or oscillation. This continues if I fret the two strings up to about the 5th fret. Perhaps the pedal is magnifying a present and normally unnoticible string/pickup interaction but it's quite apparent with the compressor on.

Any ideas?

Thanks,
Bruce