I believe Willie goes back to LA regularly, if he left Sunday night he'd be coming back on Tuesday for Wednesday practice. My best guess.
That's a good guess.
To follow the tilt this thread has taken, besides Willie, my "bump into celebrity in real life list" includes:
Gerry Cheevers, flying in first class (him, not me) on an airplane.
Joe Thornton, Sergei Samsonsov, Alisson, and Ray Bourque, at a hotel in Denver. This was when Ray was still with the Bruins - he went to play for Colorado the next year. I saw them in the evening in the hotel lobby, then the next morning in the hotel restaurant. Raymond was sitting by himself reading a newspaper, while the young guys were sitting together. I asked him for his autograph and he not only obliged, but asked me about myself. I was floored. He was such a nice guy - a real class act.
Russ Francis and a couple of other Pats of that era in Ken's Steak House. That goes back a few years!
edit: I also saw former Celtic Eric Montross buying jewelry at Natick Mall. He was a bust as an NBA player but is still a minor celebrity here in Raleigh - (he played for the Tarheels.)
Joe Horne and Oil Can Boyd in the old Filenes' Basement store in Framingham.
Robert Parish, twice, in Wayland Apothecary on Rte 30 in Wayland.
ML Carr (when he was still a player) at the Stop and Shop at 9&27.
Wilt Chamberlain, in street clothes, walking through the outer lobby in the old Boston Garden on his way to play the Celtics. I was in a small throng of people waiting for the box office to open (I was there quite early) and suddenly there was a buzz in the crowd, and I looked up just in time to see this human wall walk right in front of me! If I had stuck my foot out six inches I could have tripped him. Man, he was the tallest human being I have ever seen!
That's all I can think of right now - there are probably more.
edit: Oh, and I saw former Celtic and UNC Tarheel center Eric Montross buying jewelry in Natick Mall. (He was a bust in the NBA but is still a minor celeb here in Raleigh...)