Okay but this was kinda expected, everyone knew that the ring has such effect on the bearer even if hobbits are more resilient. I doubt Frodo was hiding the fact how he lost the finger.
Isn't this one of the reasons why Frodo went with the other bearers to go to the west when he did? He completed the whole quest and then failed at the very last step. That deep guilt weighed on him. Plus, all the trauma.