Lindelof joined United on a four-year deal on Wednesday but has inadvertently helped the club which turned him into a star.
Lindelof left the tiny eastern Sweden club for £53,000 in 2011 as a 17-year-old wonder kid, although that figure jumped to £2.6m in add-ons – the outfit’s highest ever departure.
As part of the small deal, forward thinking Vasteras stuck a 20 per cent sell on clause in the small print of the deal.
And they have returned to Portugal expecting their full share of the massive fee being negotiated with United.
Vasteras, who had already taken a complaint to world governing body FIFA that Benfica had failed to pay them £225,000 as part of the original deal once Lindelof had made 10 first-team appearances, made it clear to the Lisbon club that they wanted £7.2m of the cash United were willing to stump up.
Benfica insisted that the clause lapsed when the Swedish international signed a new contract.
After a minor squabble which threatened to derail the transfer, Vaseras pocketed a slightly less than expected but still sizable £3.6m.
Vasteras president Bengt Ake Nilsson said: “We have an agreement with Benfica. We no longer have problems with them. It is good for us.”
Lindelof played 41 times for the senior side having risen up the youth ranks and helped them to promotion to the second tier in 2010.
Vaseras were formed in 1904 and were last in the Swedish top tier, the Allsvenskan, for a one-season stop, in 1997.
They are currently managed by former Celtic hero and Bolton assistant manager Johan Mjallby – who has led the side to second after nine games this season.
To put the money changing hands, Vaseras’ highest ever purchase for a star was Canadian centre back Adam Bratz – who signed for £106,000 in 2002.