Argyle's on-loan goalkeeper David Button dived low to his right to keep out Sam Williams' penalty after Andy Williams had been fouled by Curtis Nelson in the 28th minute.
Yeovil had the better of the south west clash at Home Park, but the Pilgrims held on to extend their unbeaten run to four games.
Reid said: "That's four unbeaten but in fairness they have all been at home and the real acid test will come next because we are away for three in a row.
"That will tell me more about us. That will really test us."
On Button`s spot-kick save, Reid added: "I suppose I have got to say that it was a great penalty save by David Button.
"He did well and keepers always like to keep clean sheets and that's two he's had in the last three games now. He's a good lad David and he's done well for us."
Source: PA
Source: PA