"Tuukka Rask looking like he had some left leg discomfort at the very end of tonight's game," Haggerty tweeted. "Had to be helped off the ice by his teammates after spending some time down in the crease. Didn't look great."
However, Bruins fans could breathe a sigh of relief after Rask told reporters postgame that he was cramping because of the heat in T-Mobile Arena.
Head coach Bruce Cassidy also noted that Rask didn't suffer a serious ailment.
"He either had a little bit of a muscle pull or some dehydration, or both," Cassidy said postgame. "I don't think there's anything structurally wrong."
Rask made 31 saves (including two in the final 11 seconds) en route to Boston's third straight win to start the season. After the final horn, David Pastrnak and Jake DeBrusk assisted him off the ice, per video provided by Conor Ryan of the Boston Sports Journal.
Rask, 32, has played 13 seasons in a Bruins uniform. He saved an NHL-leading 93.1 percent of shots in 2009-10 and won the Vezina Trophy in 2013-14.
Rask backed up Tim Thomas in the 2010-11 regular season en route to his team's Stanley Cup win. He was the starter during Boston's run to the Cup in 2012-13, which ended with a loss to the Chicago Blackhawks.
After helping the Bruins to an Eastern Conference title last year, Rask started hot this season, making 28 saves in a 2-1 road win over the Dallas Stars.
The Bruins, who are just one of four teams to go undefeated through their first three games, will finish their four-game Western Conference road trip against the Colorado Avalanche on Thursday. The team returns for its home opener on Saturday against the New Jersey Devils.