Question About 3623 2002 Flag

I am putting together a collection of all the 2002-2005 flag series stamps.
I am trying to identify no. 3623. The stamp I have is the right die-cut (11.25)
date(2002),and non- denominated . The problem is that it is micro-printed (USA)
and not (USPS) as my 2022 Scott Specialized says it should be. I don't think I have discovered a new variety I must be doing something wrong. Any suggestions?
It is die-cut on 4 sides but some of the stamps from this booklet are cut on all sides. Also the backing appears to be correct. My scanner died so no pic.

did you purchase from a reputable dealer or a 'discount vendor'? If a discount vendor it is probably a counterfeit forgery. Put up some pictures. it also should say FOREVER as most 1st class are forever now, without a monetary denomination. Also, check the SC for positioning of the micro print, Different printers located the micro in different areas of the flag, (by an eyelet, white or red stripe, on the pole, etc., or none at all). I spend hours trying to determine the SC# of the flag issues and you need this SC to determine if coil or booklet & printer..

StampOCD, your stamp is 3621 from a pane of 20. Scott doesn't mention the microprinting on 3621.

Elegies, this issue predates the first Forever stamps. Before Forevers, many definitives were issued non-denominated at first, followed by denominated versions. The stamp in question is inscribed "First Class" and has a value of 37c.

I think I figured it out. This stamp must be a 3621 not 3623.
I was measuring the die cuts as 11.25x11.25.
After I remeasured several times the side cut is between 11 and 11.25. Closer to 11.1
3621 is 11.25x11.0 and is micro-printed USA.

I am NOT going to offer opinion until I HAVE researched the item both in my collection and in my Scott catalog. My apologies to the OP & to the community for being lazy & offering BAD top of the head (evidently not screwed on correctly ) information. Sometimes I think I know (and I do not)!!

for eligies, "I am NOT going to offer opinion until ..."
We've all been there, but it is big of you to admit and promise to do better!

U.S. regulars since self-stick stamps came along bigtime in mid 1990s are a wealth of varieties rivaling the so-called good old days of Washington-Franklins and so on, only the characteristics to look out for have changed. Now counterfeits come along like a flood and complicate matters too.