Well views will vary on this…the 8 AWG AL is rated for 40A depending on the rating of the terminals at both the breaker and the dryer receptacle. If the rating is not shown then you would use 60 degree column @ 310.16 of the NEC which would give us still 30A.
So ask yourself these questions…
1.) What is the rating of the terminals at both the breaker/fuse and at the dryer receptacle?
2.) Are the terminals at both ends rated for AL Wiring?
3.) Is the 8 AWG in a conduit? ( Hope Not )
Remember 8 AWG is I believe the last acceptable solid conductor before we venture into stranded conductors…except of course 6 AWG solid used for GEC’s and so on…but I digress.
Again nothing illegal about it in the eyes of the NEC, the real issue is with the terminals and knowing their ratings. If you are calling other items about for an electrical contractor to look at you could without remorse call for them to be torqued properly or check for reliable connection while the electricial contractor is their…but if that was the only issueI would not have that be a flaring issue.