do I need to clearcoat on top of solid/opaque stain (Olympic)?

I redid my deck (10x10) recently. sanded it down nice. cleaned it. let it dry. used two coats of Olympic solid stain. I can look when I get home as to which one. But am pretty sure it was stain + sealer "all in one." 26 bucks or so at Lowes. looked great for about 4 weeks. here in the Carolinas, leaves are starting to fall. And acorns and such. believe it or not...the leaves and nuts (and rust from bottom of one chair; I can sort that out) are staining the finish. and they don't come off without a lot of elbow grease. they elave little leaf outlines. its odd. so a guy came to pressure wash my home/gutters. he asked me casually if I "topcoated" it with a clear finish. Should I have done that? would that have helped? can I still do that? I guess I am naive and just believed what the can said about its durability and sealer being incorporated. again this is solid stain...not paint. can post some photos when I get home. do I need to start again and go with a different product or finishing technique? or can I give it a real good wash (and then apply some extra "layer" of clear protection? any help is appreciated. thanks