Skill mentioned in PERM application - I-140 missing?

My perm got certified recently and my attorney filed the I-140. In the certified perm , i have mentioned all my 2 previous employer and job duties.
On my 2nd previous employer i have mentioned a skill on the job duties. And its not there on the experienced letter. And the same skill available with my first employer experience letter.

Will this make issue on 140 process, can some one guide on this.

Well, it is hard to say, if they look at the specifics. Your attorney is the best person, who understands the PERM and your profile fit. So discuss with them on your concern.