ya I quite often see 350 watts out pf my 325 watt panel on my rv also and I'm farther north. in September and October, I'll only see about 320 watts out out of it.
Now on my 5th wheel I have 480 watts of 12v panels, and I have only seen 350 max out of them. my one 24V 325-watt panel on a MPPT controller consistently puts out more power than my three 180-watt 12V panels on a PWM controller
Looking into putting solar on my home, every place I have received an estimate from told me they are rated for the voltage at the end of their lifespan, so it is quite possible they could put out more power when they are new. now whether this is true or not I don't know