Cinflicting information, Hamily of Henry Dixon, www.Quakerksurmanes.net/Dixon says
Rose DIXON (b. 1661, Seagoe, Armagh, Ireland ; d. 29 Sep 1772), East Caln Twp., Chester, PA m. Thomas PIERSON (b. 1653, Pownall Fee, Chester, (Cheshire), England; d. 27 May 1734, Marple, Chester, PA) .
Thomas died 27 May 1734....
On the other hand, A report of his will Written 27 Sep 1722 says he died 29 Sep 1722, two days after making his will.
Thomas was 69, Rose was 61, could have been sickness took them both.
None of the sources I found (Ancestry.com) mentioned an unusual cause of death.