Not necessarily. I studied archaeology and one of the truisms with archaeology in the U.K. was that if you found glass it was either modern...or Roman. After the fall of the Empire we forgot how to make mineral-based glass and for a while were only making plant-based glass, which rots.

(We should be making beer bottles out of that. if beer bottles rotted, it would help our waste problems).

We are talking about 65 million years, too. The entire surface of the globe has changed. Areas that were underwater then are land now and vice versa.

Yes, we could miss it, easily enough.