Steam Ny-trenton No Red Lights Between Me And Train In Front

On my Amtrak Keystone run (train 652, Harrisburg-NY Penn) this issue occured. I was able to approach the Acela ahead of me, which was waiting for a red light, without any red signals in front of me. I stopped just in front of the last code change point inbetween me and the Acela, which the HUD indicated was yellow. The last physical signal I encountered showed 'medium approach' (solid red over flashing yellow).

My own service got delayed all the way back at Metropark, which I think caused me to be stuck behind another ACS-64 hauled service, which might be the cause for this situation occuring. After the Acela passed the next physical signal, this turned to red, and I could stop there, after which signals behaved as expected.

I'm not 100% sure this is a bug, but I don't think this should be happening.