Drew Rosenhaus, Rob Gronkowski's agent, speculates that even with Gronk retiring, there is still a possibility he could come back and play in the future. (1:35)

PHOENIX -- Rob Gronkowski announced his retirement from the NFL on Sunday, but his agent told ESPN on Monday that he wouldn't be surprised if Gronkowski reconsidered in the future.

"Rob is 29 years old. He's still a very young man. It wouldn't shock me if he has a change of heart, if he feels great and he decides that he wants to play football," Drew Rosenhaus said on Get Up!

"But this is just me talking. This isn't Rob. And I don't want to create any unnecessary expectations. Rob is a very unique personality. If the team was struggling or they needed him at some point next year, and let's just say hypothetically Tom Brady gave him a call and said 'Rob, I need you,' I wouldn't be shocked if he came back to play a few games."

Rosenhaus said that he brought up the possibility when the two talked on Sunday.

"Rob Gronkowski is retired and it's unlikely that he will ever play football again," Rosenhaus said. "However, I did close my conversation with Rob yesterday when he called to tell me he was going to retire, and I said, 'Rob, just keep in mind that if you ever have a change of heart, you can come back and play. I'm sure the Patriots would welcome you with open arms. If it's sometime during the season. If it's late in the year. If you feel good and want to come back and play, we'll make it happen.'

"That's all. It was just a suggestion. I couldn't let go without leaving that in Rob's ear. Hey listen, Jason Witten did it. Witten [is] another Hall of Fame tight end; he took the year off and decided to come back."

Asked what Gronkowski's reaction was to the possibility, Rosenhaus said: "He really was just laughing about it. He pretty much told me he's done with football at this point and he's ready to move on with his life, and football is really a thing in the past. But young guys, they can change their mind. You never know."

As for what Gronkowski plans to do now, Rosenhaus said, "Nothing. A lot of fun. A lot of rest. Good times. Relaxation. Partying. Being himself. Being Gronk. Eventually we could see him doing TV, acting, a whole number of things. Appearances. Endorsements. He's one of the biggest personalities. He won't disappear. He's going to have fun for a while, but he'll be back in the limelight in the near future, I believe."