I think that you are likely right, and have made a significant observation. The Burt dk. blue is a little bit lighter than the USPC dk. blue. The Burt Co. may have also had new molds made from the master die that included cross-hatching, which is lacking from the USPC chip.

If that lighter dark blue color was unique to Burt, it could be used to date some UFC chips. In practice, I think there was probably too much color variation at USPC and Burt to really do that.

On the other hand, if that cross-hatching is only found on Burt T-mold chips, it would be a way to date unidentified T-mold chips as being from post or pre-1947. Not really necessary with the T-mold, as there are order cards for almost all of them. In theory, though, these types of very slight mold variations could be used to broadly date chips on other molds for which we do not have records.