Hi dlcrooks,
Thank you for reaching out and posting in Apple Support Communities.
Let's see if we can help with getting your iPhone back to vibrating when receiving an incoming call while in Silent mode.
We found in the article Change iPhone sounds and vibrations - Apple Support a couple of things you can check. For details you can click on that link.
1 - If System Haptics is off, you would feel vibrations. Have you verified this feature is enabled?
2 - Is the feature Do Not Disturb enabled?
After checking those settings, if you still see this same behavior you will want to contact Apple Support by going to Get Support.
Good luck!