Claim review after 5 years

I have been receiving my CPPD benefits for 5 years. (Approved after appeal). I left my job in July 2017 as I was unable to continue to appeal was approved in October 2017. Everything has been fine for 5 years. I just received a registered letter saying I had income not reported when I applied. I fished through the papers they sent and they are referring to the T4 from my job from January 2021-July 2021 when I left. Also in the envelope where forms and documents for my doctors to complete. Should I be worried about this turn of events?

I had some income on my employer’s T4 from some compensation that I earned before I was sick that showed up later for technical reasons. Service Canada sent me a letter inquiring about it and saying that they would cut me off next month since I appeared to be back at work. I sent a detailed letter to them explaining what it was for and included a copy of various documents proving that the income was earned before I was sick and they continued my benefits.