A guild test can be taken at lvl 8, 18, 28, etc, and as you found out, if you don't take the test, your skill is capped at 10, 20, 30, etc. This will happen with all crafts, but there have been reports of a people passing into the next rank without taking the test. If you talked to the guildmaster, but he didn't ask for an item, then either you already did it or you glitched your way past the test.
If you want to know if you took the test, check your rank with this list:
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