For a moment, Dilbert, Wally, and Alice are all happy with each other. Take a look.
The extra-length Sunday strips are usually self-contained gags divorced from the (already admittedly loose) continuity of the regular strips, but there has been at least one exception: the Sunday before Christmas 1992, this strip was run, then referenced several days later here, on Christmas eve... and again here on Christmas Day. Say it with me now: n'awwwwwwwwwwwww.
A rare example of Heartwarming crossed with Nightmare Fuel, FBI agents try to talk Dilbert's mom into getting him to come out of the Elbonian Embassy so they can execute him for treason. They end up in fresh graves.
At the end of "The Gift", when Dilbert runs out of time to get Dilmom a birthday gift and has to get her a gift certificate, it looks like she's just going to treat him like a total joke yet again. However, it's let slip that Dilbert went to the mall (which he is absolutely terrified of) to look for said gift, and Dilmom seems genuinely touched.
Then he reveals the other gift he has for her: security camera footage of his father, whom neither of them had seen for years.