SB 10.12.41

śrī-rājovāca
brahman kālāntara-kṛtaṁ
 tat-kālīnaṁ kathaṁ bhavet
yat kaumāre hari-kṛtaṁ
 jaguḥ paugaṇḍake ’rbhakāḥ
Word for word: 
śrī-rājā uvāca — Mahārāja Parīkṣit inquired; brahman — O learned brāhmaṇa (Śukadeva Gosvāmī); kāla-antara-kṛtam — things done in the past, at a different time (in the kaumāra age); tat-kālīnam — described as happening now (in the paugaṇḍa age); katham bhavet — how could it be so; yat — which pastime; kaumāre — in the kaumāra age; hari-kṛtam — was done by Kṛṣṇa; jaguḥ — they described; paugaṇḍake — in the paugaṇḍa age (after one year); arbhakāḥ — all the boys.
Translation: 
Mahārāja Parīkṣit inquired: O great sage, how could things done in the past have been described as being done at the present? Lord Śrī Kṛṣṇa performed this pastime of killing Aghāsura during His kaumāra age. How then, during His paugaṇḍa age, could the boys have described this incident as having happened recently?